1. Field of the Invention
The present invention relates to a transportation-transfer device for an object of treatment used in, for example, a semiconductor manufacturing apparatus, and more particularly, to a semiconductor wafer transfer device of a resist film forming apparatus.
2. Description of the Related Art
Conventionally known are semiconductor wafer treatment apparatuses which comprise a plurality of semiconductor wafer treatment mechanisms and a delivery mechanism for carrying semiconductor wafers into and out of the treatment mechanisms. These apparatuses, which are disclosed in, for example, U.S. Pat. Nos. 4,775,281 and 4,985,722, are applied to resist film forming apparatuses, developing apparatuses, etc.
In a resist film forming apparatus disclosed in U.S. Pat. No. 4,985,722, two forks are arranged for movement from side to side along a transportation path, and wafer carriers loaded with semiconductor wafers without resist film thereon and wafer carriers for storing semiconductor wafers with resist film formed thereon are arranged on one side of the transportation path. A cooling mechanism, applicator mechanism, and baking mechanism are arranged on the other side of the transportation path. The cooling mechanism serves to adjust the wafers transported from the wafer carriers to a predetermined temperature. The applicator mechanism is used to apply the resist film to the wafers delivered from the cooling mechanism. In the baking mechanism, the semiconductor wafers coated with the resist film by means of the applicator mechanism are subjected to heat treatment.
Each of the two forks has a holding section, e.g., vacuum suction means, for holding each semiconductor wafer. Also, each fork is provided with a mechanism for moving the holding section to each wafer carrier and the position of each treatment mechanism in which the wafers are placed. In this arrangement, the semiconductor wafers can be successively delivered from the wafer carriers to the treatment mechanisms, and finally stored in the carriers.
While one semiconductor wafer is being carried out from one of the treatment mechanism, in the above-described apparatus having the two forks, another wafer to be treated next can be carried into the same treatment mechanism to be set therein. Accordingly, the time required for a treatment process can be shortened.
Since the semiconductor wafers are transported by moving the forks along the transportation path in the aforesaid manner, moreover, only one transportation mechanism can accomplish the transportation of the wafers between a plurality of treatment mechanisms. Thus, the apparatus can be reduced in size.
If the single transportation mechanism is bound to manage the wafer transportation between the treatment mechanisms, however, the temperature of each fork is increased by heat from each semiconductor wafer as the wafer is transported from the baking mechanism to one of the wafer carriers. When the semiconductor wafer to be treated next is transported from the cooling mechanism to the applicator mechanism, therefore, it is heated by the fork, so that the wafer temperature is inevitably deviated from the temperature set by means of the cooling mechanism.
When one of the two forks of the transportation mechanism increases, its heat is transmitted through ambient gas to the other fork. Even in the case where a semiconductor wafer is transported from the cooling mechanism to the applicator mechanism by means of that fork which does not engage in the transportation of the wafer from the baking mechanism to the wafer carrier, therefore, the newly transported wafer is undesirably heated in the same manner as aforesaid.
These problems are not limited to the case where the transportation-transfer device is applied to the resist film forming apparatus, and also arise when the device is applied to any other apparatus, such as a developing apparatus.